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由于前人在自然界没有找到过金的硫化物,因此硫金银矿(Liujiyinite)[1]以及沃登堡矿(据Uytenbogaardtite译音)[2]的相继发现,引起了矿物学家的极大兴趣。 相似文献
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海南岛南岸的珊瑚礁,是我国全新世珊瑚岸礁最为发育的地区之一,仅次于台湾岛南端的恒春半岛沿岸。前人从生物学[1-5]、地貌学[6-8]和地质学[9-12]角度对海南岛南岸的珊瑚礁进行过较为广泛的研究。作者报道过崖县鹿回头水尾岭剖面珊瑚礁样品的C14年代测定结果[13,14]。1979年底至1980年初,作者在海南岛南岸东起小东海沿岸西至西瑁岛西岸地区进行了野外调查与采样。根据野外和室内分析资料,本文公布了一批新测试的C14年代数据,并进一步讨论了全新世珊瑚礁的发育历史及其与海岸变迁、海面变化和地壳运动的关系等问题。 相似文献
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氟是磷灰石的重要化学组成之一[1]。磷块岩和磷灰石中氟的测定,对磷灰石类型的鉴定和磷块岩的成因研究有重要意义。目前,氟的测定方法广泛地采用酸、碱溶(融)样,用蒸馏法进行元素分离[2,3,4]。近十几年来,由于离子选择电极法操作方便,被广泛地应用于各种类型物质中氟的测定[5]。离子交换剂可以用来分解某些难溶性的天然和合成材料,但是至今这个方法还未得到广泛地应用。 相似文献
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矿物中的水分为结晶水,结构水(氢氧根)、层间水、沸石水和吸附水等几种结构状态。不同结构状态的水对矿物的性质应有不同的影响。但是著名矿物学家拉尔森[1](E.S.Larsen)给定矿物中水的比折射度k值(又称格拉斯顿-代尔常数),不论是对何种结构状态的水都适用。曾经有许多人对这一点产生过疑义,最近曼达利诺[2](J.A.Mandarino)修正k值时,对各种结构状态的水仍是同用一值。矿物中各种水的折射度是否变化呢?本文作者将列举大量数据来说明这一问题。 相似文献
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苏州高岭土矿床可划分为两种成因类型[1,2],即风化型1)和热液蚀变型。高岭土集中分布在阳山东、西、北三个矿区。本文仅就阳西风化型高岭土中产出的不同种类高岭土矿物的形成及其互相演变的关系作初步探讨。 相似文献
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关于鄂尔多斯断块[1]及其周缘的寒武纪地层与海侵,卢衍豪先生曾有论述。本文将讨论“霍山砂岩”的时代及其时侵的特点。 相似文献
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昂仁组是一套复理石和类复理石沉积,含晚白垩世土伦期的菊石Mammites[1,2],但因未发现直接的上覆地层和化石稀少而不能肯定是否还包括晚于土伦期或至早第三纪的沉积[1,3]。1980年,笔者在昂仁、萨噶一带的昂仁组中采到瓣鳃、腹足化石;我局区调队在仲巴县错江顶一带,发现连续沉积于昂仁组之上,整合于下第三系之下一套含Masstrichtian期菊石(Sphenodiscus)的杂色地层。本文报道这一发现和对昂仁组时代问题的认识(图1)。 相似文献
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The Late Proterozoic Conception Group, exposed on the Avalon Peninsula in Newfoundland, Canada, is a 4 km thick turbidite succession containing a conformable 300 m thick sequence of diamictites (the Gaskiers Formation) near the base. Massive and crudely-stratified diamictites form beds up to 25 m thick which have a tabular geometry with slightly erosive basal contacts and are interbedded with mudstones and fine-grained, thin-bedded turbidites. These diamictites are interpreted as submarine debris flow deposits. Disrupted diamictites form strongly deformed units that contain large, complexly folded rafts of mudstone and turbidite facies. These diamictite units are interpreted as submarine slumps. Diamictites contain glacially-striated and faceted clasts; clasts and matrix are predominantly of volcanic provenance. One outcrop shows interbedded volcanic agglomerate and diamictite, and volcanic bombs can also be identified. The interbedding of diamictites with turbidites and the stratigraphic context provided by the thick sequences of turbidites below (Mall Bay Formation) and above (Drook Formation) indicate a deep marine slope setting of diamictite deposition. Diamictite facies record remobilization and downslope transfer of large volumes of unstable volcanic and glacial debris initially deposited in a shallower water marginal marine zone. The regional tectonic framework suggests the Conception Group accumulated in a deep, southward-opening ensialic rift basin with active but waning volcanic centres to the north. The Gaskiers Formation may be representative of other Late Precambrian glacially-influenced diamictite sequences that were deposited around the North Atlantic region and in Europe. These deep marine diamictite sequences characterized by debris flows, turbidites, and slump deposits, can be contrasted with more extensive shallow marine shelf diamictite sequences found in association with dolomites and tidally influenced shallow water facies in other basinal settings. 相似文献
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Facies and Architecture of a Carboniferous Grounding-line System From the Guandacol Formation, Paganzo Basin, Northwestern Argentina 总被引:1,自引:0,他引:1
New outcrops of Middle Carboniferous glacigenic deposits found in the Guandacol Formation (western Paganzo Basin) are described in this paper. The study locality of Los Pozuelos Creek (northwestern Argentina) includes coarse-grained diamictites, rhythmites, laminated pebbly mudstones and shales that represent an expanded column of the Gondwanic glaciation in this region. Thirteen lithofacies recorded at the measured section have been grouped into three facies associations. Facies Association I is composed of coarse-grained massive and stratified diamictites (lithofacies Dmm, Dms, Dmg, Dcs), laminated siltstones with dropstones (Fld) and interstratified sandstones and mudstones (Fl, Sr). These rocks represent both tillites and resedimented diamictites closely associated to small water bodies where laminated siltstones with dropstones and stratified sandstones and mudstones were deposited. Facies Association II comprises couplets of matrix-supported thinly bedded diamictites (Dmld) and laminated mudstones with dropstones (Fld). This facies association results from the combination of three different processes, subaqueous cohesionless debris flows, coeval rainout of ice-rafted debris and settling of fine-grained particles from supension. Finally, Facies Association III is made up of laminated mudstones without dropstones, thin marl levels and scarce fine- to very fine-grained sandstones. This assemblage clearly suggests sedimentation in a deep marine environment below the wave base.The architecture of the glacigenic deposits has been investigated using photomosaic panels. The geometry of the depositional bodies and facies suggest that Los Pozuelos Creek outcrops exhibit a well preserved three-dimensional example of a grounding-line system. In particular, three different subenvironments of a morainal bank were interpreted: a bank-front, a bank-core and a bank-back. The bank-front assemblage is characterized by coarse-grained, mainly resedimented, diamictites grading laterally to prograding clinoforms composed of interbedded matrix-supported thinly bedded diamictite and mudstones. The bank-core assemblage is formed by a stacking of coarse-grained diamictites where at least five major erosional surfaces, bounding four multistory diamictite bodies, can be recognized. Finally, the bank-back assemblage corresponds to discontinuous intervals of striated lodgement till, and coarse-grained resedimented diamictites showing important post-depositional deformation. The retrogradational stacking of the morainal banks indicate an overall glacial retreat and a glacioeustatic sea-level rise. Erosional surfaces at the base of each morainal bank suggest intervening short term episodes of ice advance.The new data presented here confirm the existence of "true" tillites in western Paganzo Basin and suggest several (at least four) pulses of glacial advance and retreat during the Namurian glaciation in the region and permit a more refined interpretation of the glacial deposits in the Huaco area. 相似文献
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The origin of the Luoquan Formation which occurs along the southern margin of the North China Blockhas long been argued. Based on recent work. the Formation is considered as a glacial sedimentary sequencepartially reworked by sediment gravity flow. The major evidence for the glacigene of Luoquan Formationdiamictites is as follows: 1, a striated and polished pavement with various features resulting from glacialabrasion and plucking, such as crescentic gouge, crescentic fracture, streamlined form and glaciated step; 2.unsorted diamictites with striated clast. faceted clast and iron-shaped stone formed by glaciation; 3. rhythmitewith dropstones; 4. a glacial sedimentary sequence bearing advance-retreat cycles; and 5. wide distribution ofthe diamictites. Glacial deposits can be distinguished from sediment gravity flow deposits by the features men-tioned above. Some characteristics of sediment gravity flow existing in the Luoquan Formation diamictites in-dicate that glacial deposits might have been partially reworked by sediment gravity flow. Therefore, this papersuggests that the Luoquan Formation diamictite is a result of a glacial event rather than a mud flow deposit.The primary tillites are the principal contribution of the Luoquan Formation, while sediment gravity flow de-posits are the redeposited diamictites and should be termed as glacigenic sediment gravity flow deposits. 相似文献
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冰碛岩中常存在一些变形构造,国外屡见报道,但国内报导甚少。本文以豫西上震旦统罗圈组冰碛岩为例,采用形态分类法,将冰碛岩的变形构造分为向斜状构造,褶曲构造与楔状和脉状构造。这些变形构造分别赋存于各不相同的冰碛岩中,其成因也各异。向斜状构造最可能的成因是沉积物重力负载的作用,褶曲构造是冰湖滨岸带堆积物沿斜坡滑动的产物,相当于滑塌构造;楔状构造则可能是冰缘环境的冰楔体融化泄水的结果;脉状构造虽赋存形态多样,但却均由相似的成因机制,即饱和液化砂顺裂缝贯入形成的。 相似文献
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摘要:本文首次对区内杂砾岩(又称红层)的沉积学特征进行研究。据成因之不同,把杂砾岩区分为6类:泥石流、颗粒流、泥流、冲刷砾石层、河道及片流沉积。讨论了各类沉积之特点,尤其是砾石的粒度分布特征。结果表明,不同成因的杂砾岩砾石的粒度分布曲线形态,尤其是量化粒度参数存在明显差异。 相似文献
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云南大理点苍山末次冰期冰碛物石英砂扫描电镜形态特征分析 总被引:5,自引:1,他引:4
云南大理点苍山是大理冰期的命名地,保存有确切的末次冰期冰川作用遗迹.对点苍山冰碛物石英砂进行了扫描电镜形态特征分析,获得了其石英砂形态特征及其频率,并在冰川成因的典型特征的频率上取得了新的认识.扫描电镜分析表明,点苍山冰碛物石英砂形态特征主要为:石英砂形状主要为次棱角状、尖棱角状和多棱角状,边缘多可见次棱脊和棱脊磨损,表面起伏度高;机械特征主要有贝壳状断口、平行解理面、裂隙、粘附碎片、擦痕、机械V形坑;化学特征主要有蚀坑和蚀缝、蜂窝状溶蚀表面、无定形硅沉淀和硅质薄膜.在石英砂表面与冰川作用密切相关的擦痕的频率为8%~32%;粘附碎片的频率为16%~40%;裂隙的频率为12%~32%.通过对点苍山冰碛物的石英砂扫描电镜分析,得出该第四纪海洋性冰斗冰川和悬冰川的石英砂形态特征及其频率.该冰碛物石英砂原始形态特征明显,机械特征频率不高,是近源堆积的冰碛物石英砂的典型形态特征. 相似文献
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云南大理苍山世界地质公园具有较高的美学价值与地学科研价值,在地学研究领域中苍山又被称为点苍山。本次研究的主要区域是点苍山玉局峰北坡和点苍山西北部的罗坪山大小海子地区,本文对点苍山玉局峰北坡冰碛物和罗坪山第四纪沉积物进行了光释光年代测定,讨论了光释光测年方法在点苍山地区第四纪冰碛物测年中的适用性,测得玉局峰北坡搬运距离较远的三条冰碛垄的年龄为(31.68±3.22)~(28.01±1.95)ka BP,属于末次冰期。对罗坪山地区第四纪沉积物进行石英砂扫描电镜分析,观察到大小海子附近第四纪沉积物石英砂表面具有一定的冰川成因特征,推断罗坪山大小海子地区曾发育过第四纪冰川作用,通过光释光测年得到大小海子附近冰川沉积物年代为(136.36±10.16)ka BP,相当于倒数第二次冰期。结合前人研究,推断点苍山地区也具有发育倒数第二次冰期的可能性。 相似文献